For many years, vehicles such as automobiles, light trucks, vans, and recreation vehicles have utilized a construction method known in the industry as body-on-frame construction. With body-on-frame construction, a vehicle body is mounted on a vehicle frame by resilient isolators. Typically, the body has been spaced away from the frame by a fairly wide gap of 25 mm or more, to provide a built in allowance for dimensional variations in the frame and the body, rubber compression of the isolators, and other manufacturing concerns, so that the body will not contact the frame directly under either static or operating loads. It has also been common practice to route components such as brake lines and wiring harnesses through the gap between the body and frame, so that they will be protected from damage.
FIG. 1 shows several components of a prior body-on-frame apparatus 100, to illustrate the manner in which the body 112, as represented by a cross member 113 of the body 112, is mounted in a spaced relationship to the frame 114, to form a gap 118 having a vertical dimension designated as D1. As stated above, in the past, the gap 118 between the body 112 and frame 114 has had a dimension D1 that is fairly wide, on the order of 25 mm or more, so that the body 112 will never contact the frame 114 during operation of the vehicle, as a result of either general movement of the entire body 112 with respect to the frame 114, or as a result of localized deflection of a portion of the body 112 due to localized loads applied to the body 112 by load bearing structures, such as the passenger seating structure 111 shown in FIG. 1.
The National Highway Traffic Safety Administration, of the United States Department of Transportation, has promulgated regulations FMVSS 213 and FMVSS 225, relating to the design and testing of Child Restraint Anchorage Systems in vehicles, which limit the total amount of localized deflection of body 112 and seating structures 111 attached to the body 112 that is allowable under specified loading conditions, which are selected to emulate the operating load imposed on the body 112 of a vehicle during a collision, by a child restraint apparatus holding a child while anchored to a seating structure 111 of the vehicle.
Through the years that FMVSS 213 and FMVSS 225 have been in force, the level of the operating load applied during testing has been increased periodically, and the amount of deflection that is allowable has been decreased. These changes in the regulations have required that portions of the seating structure 111, and components of the vehicle body 112 such as the crossmember 113 be made stronger and more resistant to bending under the forces exerted by the operating loads specified in FMVSS 213 and 225. Generally this has required the addition of reinforcing components, such as doublers, or increasing the thickness of the material used in the components of the seating structure 111, the crossmember 113, and other parts of the vehicle body 12. Adding these components and increasing the material thickness undesirably increases the cost, weight and complexity of the body-on-frame apparatus of the vehicle.
For vehicles entering service after Sep. 1 of 2004, the operating loads required by FMVSS 225 have once again been increased to be 50 percent higher than the loads previously required. It is highly desirable that an apparatus and method be provided for handling these additional loads without further increasing the cost, weight, and complexity by resorting to the prior practice of adding yet more reinforcing components and/or increasing the material thickness of prior components. It is also highly desirable that an apparatus and method be provided that will handle the new, higher loads, and allow a reduction in the cost, weight and complexity of the body-on-frame apparatus.